[quote=@Baconator]
Yes, Your character would be fine. The banishment of lesser undead and demons via prayer is strictly lesser undead. IE: Zombies, ghouls, skeletons, ect. the typical rabble of undead that make up the horde. And his armor does not nullify dark magic completely, it only dulls its effects. So a spell intended to syphon the soul from someone's body and feed it to the caster would leave him disorientated and weary as opposed to killing him and draining his soul.  
[/quote]

What would a lethal dose of mundane, nonmagical poison do to him?